Steven J. Oosterling

The perioperative period is an underutilized window of therapeutic opportunity in patients with colorectal cancer.

Objective:In this review, we address the underlying mechanisms by which surgery augments metastases outgrowth and how these insights can be used to develop perioperative therapeutic strategies for prevention of tumor recurrence. Summary Background Data:Surgical removal of the primary tumor provides the best chance of long-term disease-free survival for patients with colorectal cancer (CRC). Unfortunately, a significant part of CRC patients will develop metastases, even after successful resection of the primary tumor. Paradoxically, it is now becoming clear that surgery itself contributes to development of both local recurrences and distant metastases. Methods:Data for this review were identified by searches of PubMed and references from relevant articles using the search terms “surgery,” “CRC,” and “metastases.” Results:Surgical trauma and concomitant wound-healing processes induce local and systemic changes, including impairment of tissue integrity and production of inflammatory mediators and angiogenic factors. This can lead to immune suppression and enhanced growth or adhesion of tumor cells, all of which increase the chance of exfoliated tumor cells developing into secondary malignancies. Conclusions:Because surgery remains the appropriate and necessary means of treatment for most CRC patients, new adjuvant therapeutic strategies that prevent tumor recurrence after surgery need to be explored since the perioperative therapeutic window of opportunity offers promising means of improving patient outcome but is unfortunately underutilized.

Macrophages direct tumour histology and clinical outcome in a colon cancer model

Macrophages generally constitute a major component of the tumour stroma. Although conventionally considered to be cytotoxic effector cells, macrophages have recently been described as promoters of tumour progression. The present study shows that selective depletion of peritoneal or liver macrophages prior to CC531 tumour cell inoculation resulted in highly differentiated tumours in rats. In contrast, tumours from control rats, in which macrophages are abundantly present, showed a desmoplastic stromal reaction with hallmark features of malignancy, such as neovascularization and matrix remodelling, indicating that the presence of macrophages is associated with malignant histopathological differentiation. Remarkably, macrophage‐depleted rats, bearing highly differentiated tumours, had a worse prognosis, as they displayed a higher tumour load and poorer survival. Thus, while macrophages direct tumours towards malignant tumour histology, their role in anti‐tumour defence is important. The selective inhibition of macrophage functions involved in malignant progression without interfering with cytotoxic ability may therefore identify important new targets for cancer therapy. Copyright

Blocking α2 integrins on rat CC531s colon carcinoma cells prevents operation‐induced augmentation of liver metastases outgrowth

Currently, an operation is the only curative option for patients with colorectal cancer. Unfortunately, many patients will develop liver metastases even after successful resection of the primary tumor. Removal of primary colorectal carcinoma may paradoxically increase the risk of metastases development, because accumulating evidence suggests that surgical trauma can stimulate tumor growth. In the present study, we investigated the effects of abdominal trauma on liver metastases development. Surgical trauma dramatically increased adhesion of tumor cells in the liver, leading to enhanced outgrowth of metastases. Endothelial stress was observed rapidly after an operation, suggesting that abdominal trauma resulted in impairment of blood vessel integrity. Tumor cells preferentially adhered to extracellular matrix (ECM). Furthermore, preincubation of tumor cells with anti‐α2 integrin antibodies completely reverted operation‐induced augmentation of CC531s adhesion and liver metastases outgrowth. As such, we postulate that blood vessel integrity in the liver is compromised after abdominal trauma, resulting in enhanced ECM exposure, which enables tumor cell adhesion and metastases outgrowth. Conclusion: Perioperative treatments that either aim to reduce endothelial stress or block the interaction between tumor cells and ECM represent promising new therapeutic strategies for the prevention of liver metastases development after resection of the primary tumor. (HEPATOLOGY 2007.)

Anti-β1 Integrin Antibody Reduces Surgery-Induced Adhesion of Colon Carcinoma Cells to Traumatized Peritoneal Surfaces

Objective:To study the mechanisms behind surgery-induced augmentation of tumor outgrowth. Summary Background Data:Surgery provides the best chance of cure for most primary intra-abdominal carcinomas. Effective treatment is however relatively frequent complicated by peritoneal recurrences, which often originate from free-floating intraperitoneal tumor cells that implant on peritoneal surfaces. We previously reported that surgical trauma promotes development of peritoneal metastases. Methods:Evaluation of adhesion of CC531s rat colon carcinoma cell line intraperitoneally after laparotomy using in vivo, ex vivo, and in vitro models. Also, human ex vivo models were used to study peritoneal tumor cell adhesion. Results:Peritoneal imprints of operated rats showed that direct damaging of the peritoneum resulted in enhanced adhesion of rat CC531 colon carcinoma cells to submesothelial extracellular matrix (ECM) proteins in vivo, which was confirmed by electron microscopy. Additionally, the inflammatory reaction of the peritoneal cavity led to retraction of mesothelial cells, hereby also exposing ECM at peritoneal surfaces that had not been traumatized directly. Furthermore, we demonstrated that β1 integrin subunits represented the primary mediators involved in adherence to either isolated ECM components or excised traumatized rat and human peritoneum. Importantly, incubation of CC531s cells with anti-β1 integrin antibodies resulted in a significant decrease of tumor cell adhesion in vivo. Conclusions:Surgical trauma results in exposure of ECM at directly and nondirectly damaged peritoneal surfaces, leading to increased β1 integrin-dependent tumor cell adhesion. Perioperative therapies, which aim to block β1 integrin subunits, might therefore serve as new clinical tools for the prevention of peritoneal recurrences.

The role of macrophages in tumor development.

Macrophages constitute a large proportion of the immune cell infiltrate, which is present in many tumors. Activation state of macrophages is greatly influenced by their environment, leading to different macrophage subsets with diverse functions. Although previously regarded as potent immune cells that are capable of destroying tumor cells, recent literature focuses on the ability of macrophages to promote tumor development due to secretion of mediators, like growth and angiogenic factors. It is now becoming increasingly clear that a complicated synergistic relationship exists between macrophages and malignant cells whereby tumor cells can affect macrophage phenotype, and vice versa. As such, macrophages and their contribution in cancer development are currently subject of debate.

Experimentally induced liver metastases from colorectal cancer can be prevented by mononuclear phagocyte-mediated monoclonal antibody therapy

BACKGROUND & AIMS Development of liver metastases is a frequent complication in patients with colorectal cancer (CRC), even after successful resection of the primary tumor. As such, post-operative adjuvant therapies that aim to eliminate residual disease after surgery may improve patient outcome. METHODS We used a colon carcinoma liver metastases model, in which CC531s colon carcinoma cells are injected into the portal circulation by a surgical procedure. As injected tumor cells are arrested in the liver, this model is suitable for investigating the interaction of tumor cells with the liver microenvironment. By administering tumor specific monoclonal antibodies (mAb) directly post-operatively, we were able to determine the effect of antibody therapy on eradication of arrested tumor cells and subsequent liver metastases outgrowth. RESULTS We showed that post-operative treatment with tumor specific monoclonal antibodies (mAb) prevents liver metastases outgrowth. Antibody-dependent phagocytosis (ADPh) was the main mechanism involved, as enhanced uptake of tumor cells by innate mononuclear phagocytes in the liver was observed after mAb therapy. Furthermore, Kupffer cells (KC) were identified as the most prominent effector cells, as depletion of KC abolished therapeutic efficacy. This was partly compensated by monocytes when animals were treated with a high mAb dose, but monocytes were unable to phagocytose tumor cells when rats were treated with low mAb doses. CONCLUSIONS The finding that KC and monocytes can eliminate tumor cells through ADPh has important and promising clinical implications for designing new adjuvant therapies for patients undergoing CRC resection.

Tumor infiltrating macrophages reduce development of peritoneal colorectal carcinoma metastases

Macrophages generally constitute a major component of tumor stroma, and possess either tumor growth promoting or inhibiting capabilities. Classically activated macrophages exert cytotoxicity and produce inflammatory cytokines, which limits tumor growth. By contrast, alternatively activated or M2 macrophages induce tumor progression by stimulating angiogenesis and proliferation. Previously we showed that resident macrophages control metastatic spread of coloncarcinoma cells in liver and peritoneal tumor models. However, it is proposed that newly recruited macrophages develop into tumor-associated M2 macrophages, as they are exposed to a microenvironment that favors alternative activation. Previously we showed that monocyte migration was diminished after flavonoid treatment in an experimental autoimmune encephalomyelitis animal model. In the present study, we investigated the role of newly recruited macrophages in colon carcinoma development, by using the flavonoids rutin and luteolin to reduce monocyte migration into peritoneal tumors. Increased tumor development was observed in animals that were treated with rutin and luteolin. Immunohistochemical analyses showed that the number of ED2(+) resident macrophages was normal in tumors of animals that received rutin and luteolin treatment. However, the number of ED1(+) cells (marker immature macrophages) was reduced, indicating decreased macrophage recruitment. Thus, inhibition of monocyte migration promotes tumor growth, supporting that not only resident, but also newly recruited macrophages limit peritoneal colon carcinoma metastases development.

Taurine and the Relevance of Supplementation in Humans, in Health and Disease

Taurine, a beta-sulphur amino acid with a zwitterionic function, plays an important role in several biological processes. In humans taurine synthesis is limited. Therefore, intake by food is important. A normal diet, including animal products, contains a sufficient amount of taurine to provide the physiological necessary quantity of taurine. Taurine is a component of bile salts, which function as detergents for emulsification of dietary lipids and fat-soluble vitamins. Also, taurine is involved in the development of the brain and retina, which makes it an essential nutritional substrate in neonates and small children, who are limited in the synthesis of taurine. Moreover, taurine can act as an osmoregulator and antioxidant, which makes it an important amino acid during pathological conditions such as ischemic reperfusion injury, inflammation and brain oedema. Its osmolytic function helps to prevent alteration in the intra-cellular concentrations of all substances. In many models of oxidant-induced injury, taurine was shown to be tissue-protective as a non-toxic endogenous antioxidant. This review focuses on the biological actions of taurine, to illuminate possible clinical benefits of taurine.

Hypertaurinemia in Bile Duct–Ligated Rats After Surgery: The Effect of Gut Endotoxin Restriction on Organ Fluxes and Oxidative Status

Surgery in obstructive jaundice is associated with complications related to gut-derived endotoxemia. The organs involved in these complications, including liver, kidneys, and gut, are important in the metabolism of taurine, which is implicated in bile acid conjugation and has antioxidative effects. Taurine organ metabolism and liver oxidative status were studied in bile duct-ligated rats (BDL) after laparotomy. Oral cholestyramine treatment inhibits gut-derived endotoxemia and was used to evaluate the role of endotoxin. In BDL rats, postoperative plasma taurine levels were higher compared with SHAM (p < .0001). Cholestyramine treatment reduced plasma taurine in BDL rats (p < .005), but levels remained higher compared with SHAM groups (p < .0001). In contrast to a liver uptake of taurine in SHAM rats, a release from livers of BDL rats was found (p < .005). Cholestyramine treatment in BDL rats resulted in a liver uptake of taurine (p < .05 vs BDL). A higher uptake of taurine by the kidneys was found in both BDL animals after surgery and SHAM controls (p < .005); however, cholestyramine had no effect. A release of taurine from the gut was found in the SHAM groups, which was reversed in both BDL groups (p < .01). Cholestyramine lowered the elevated levels of hepatic enzymes in BDL rats (ALT and AST: p < .05). Total liver glutathione levels were lower in BDL rats (p < .0001) compared with SHAM groups, and cholestyramine significantly attenuated this decrease (p < .01). Liver malondialdehyde levels were higher in BDL rats compared with SHAM (p < .01), whereas cholestyramine completely prevented this increase in lipid peroxidation (p < .0001). Hypertaurinemia in BDL rats after surgery is most likely explained by reduced bile acid conjugation and hepatocellular leakage. Cholestyramine treatment reduced hepatocellular damage by inhibiting gut-derived endotoxemia, and reversed the release of taurine from the jaundiced liver into an uptake and consequently lowered plasma taurine levels. This uptake may contribute to the improved antioxidant status in cholestyramine-treated BDL rats.

Spillage of bacterial products during colon surgery increases the risk of liver metastases development in a rat colon carcinoma model.

ABSTRACT Surgical resection of the primary tumor provides the best chance of cure for patients with colorectal carcinoma (CRC). However, bacterial translocation during intestinal surgery has been correlated with poor long-term oncological outcome. Therefore, we investigated the influence of bacterial contamination during colon surgery on CRC liver metastases development. Blood and liver samples of patients undergoing resection of primary CRC or liver metastases were collected. Cell numbers, activation markers and inflammatory mediators were determined. Tumor cell adhesion and outgrowth after sham- or colectomy operations were determined in a rat model, in which tumor cells had been injected into the portal vein. White blood cells and granulocytes were increased in per- and post-operative patient blood samples. IL-6 was also increased post-operatively compared to the preoperative level. Expression of NOX-2, NOX-4 and polymorphonuclear cells (PMNs) numbers were elevated in post-operative human liver samples. In vitro stimulation of macrophages with plasma of rats after colectomy resulted in production of reactive oxygen species (ROS). Colectomy in rats increased D-lactate levels in plasma, supporting bacterial translocation. Decreased expression of tight junction molecules and increased tumor cell adhesion and outgrowth was observed. Treatment with a selective decontamination of the digestive tract (SDD) cocktail decreased tumor cell adherence after colectomy. In conclusion, postoperative bacterial translocation may activate liver macrophages and PMNs, resulting in ROS production. As we previously showed that ROS release led to liver vasculature damage, circulating tumor cells may adhere to exposed extracellular matrix and grow out into liver metastases. This knowledge is pivotal for development of therapeutic strategies to prevent surgery-induced liver metastases development.